This invention relates to a light-sensitive silver halide photographic material which gives images of high contrast, more particularly to improvement of trouble generated in high contrasting technique with a hydrazide compound.
In recent years, in the field of printing photomechanical process, color formation and complication of printing are under remarkable progress. Accordingly, improvement of quality and stability of quality for light-sensitive silver halide photographic material for printing (hereinafter called printing sensitive material) which is the intermediate medium for printing have been increasingly demanded year by year. In the prior art, printing sensitive material has been generally endowed with the so called "lith development" processing aptitude for accomplishing high quality. However, in "lith development", it is impossible in mechanism to contain sulfite ion which is the preservative at high concentration in the development processing solution, and therefore stability of the developer is very poor, as is well known to those skilled in the art.
As the technique for cancelling instability of "lith development", and obtaining images of high contrast comparable to the "lith development", some attempts can be found in disclosures of patent literatures. For example, techniques for obtaining tone hardened images by use of hydrazide compounds are disclosed in Japanese Unexamined Patent Publications Nos. 16623/1978, 20921/1978, 20922/1978, 49429/1978, 66731/1978, 66732/1978, 77616/1978, 84714/1978, 137133/1978, 37732/1979, 40629/1979, 52050/1980, 90940/1980, 67843/1981 and others. In the processing method in the image forming method by use of these hydrazide compounds, in order to obtaining an image of high contrast, it is required that the pH value of the developer containing the hydrazide compound or pH value of the processing developer for the light-sensitive photographic material containing the hydrazide compound should be at high level, and such high pH value disadvantageously lowers the effective life of the developer.
In contrast, in Japanese Unexamined Patent Publication No. 106244/1981, it is described that an image of high contrast can be formed at relatively lower pH (11-11.5) by having a hydrazide compound and a development promoting amount of an amino compound contained during formation of image.
The image forming method by use of these hydrazide compounds can obtain images of very high contrast. Generally speaking, development processing solution may suffer from fog generation, etc. undesirable in photographic performance when no adequate development supplementing agent is supplemented, but in the method by use of hydrazide, even when the fatigue degree of the development processing solution is not so great, generation of black dots like black sesame (hereinafter called pepper fog) is seen at the unexposed portion, for example, between the dots during halftoning by use of a contact screen in printing sensitive material, whereby a trouble may be caused to occur which can be a vital defect in commercial value. In Japanese Unexamined Patent Publications Nos. 16623/1978 and 20921/1978 as previously mentioned, generation of fog containing pepper fog as mentioned above is inhibited by incorporating benzotriazole which is an inhibitor in the silver halide photographic emulsion, but its effect is not sufficient, and high contrast may be sometimes impaired, and it can hardly be said to be a completed technique.
The present inventors have studied intensively and consequently have developed a light-sensitive silver halide photographic material which does not impair high contrast while inhibiting the fog including pepper fog which is the drawback of the tone hardening technique by use of a hydrazide compound.